Characteristics of Puberty in a Population-Based Sample of Danish Adolescents.

Purpose: To describe the duration, timing, tempo, and synchronicity of puberty, as well as the correlation between timing and tempo of puberty.

Methods: Overall, 15,819 of 22,439 invited children participated in the Puberty Cohort within the Danish National Birth Cohort. Participants completed a web-based questionnaire every 6 months through maturation with questions on current pubertal status.

Prenatal exposure to nitrosatable drugs and timing of puberty in sons and daughters: A nationwide cohort study.

Background: N-nitroso compounds (NOCs) can be formed by endogenous reactions between nitrosatable drugs and nitrite. Animal studies have found that several NOCs are teratogenic, and epidemiological studies report associations between prenatal exposure to nitrosatable drugs and adverse birth outcomes. It is unknown whether prenatal exposure to nitrosatable drugs is harmful to the child's reproductive health, including pubertal development.

Maternal Intake of Vitamin D Supplements during Pregnancy and Pubertal Timing in Children: A Population-Based Follow-Up Study.

Maternal vitamin D may be important for several organ systems in the offspring, including the reproductive system. In this population-based follow-up study of 12,991 Danish boys and girls born 2000-2003, we investigated if maternal intake of vitamin D supplements during pregnancy was associated with pubertal timing in boys and girls. Information on maternal intake of vitamin D supplements was obtained by self-report in mid-pregnancy.

Timing of puberty in relation to semen characteristics, testicular volume, and reproductive hormones: a cohort study.

Objective: To investigate whether the timing of puberty is associated with semen characteristics, testicular volume, and reproductive hormone levels.

Design: Cohort study.

Setting: Not applicable.

The estimated effect of season and vitamin D in the first trimester on pubertal timing in girls and boys: a cohort study and an instrumental variable analysis.

Background: Season of birth has been associated with age at menarche. Maternal vitamin D levels in pregnancy may explain this effect. We investigated whether the season of first trimester or maternal 25-hydroxyvitamin D3 [25(OH)D3] levels were associated with pubertal timing in children.

Maternal intake of folate and folic acid during pregnancy and pubertal timing in girls and boys: A population-based cohort study.

Background: Folate is essential for normal foetal development as it plays an important role for gene expression during different periods of foetal development. Thus, prenatal exposure to folate may have a programming effect on pubertal timing.

Objectives: To study the association between maternal intake of folate during pregnancy and pubertal timing in girls and boys.

Prenatal nitrate exposure from diet and drinking water and timing of puberty in sons and daughters: A nationwide cohort study.

Background: In Western countries, age at pubertal development has declined during the last century in girls, and probably also in boys. No studies have investigated whether nitrate, a widespread environmental exposure with teratogenic and hormone disrupting properties, might affect timing of puberty.

Objectives: We investigated if prenatal exposure to nitrate from drinking water and diet was associated with timing of puberty.

Maternal polycystic ovarian syndrome and pubertal development in daughters and sons: a population-based cohort study.

Study Question: Does maternal polycystic ovarian syndrome (PCOS) affect the timing of pubertal development in daughters and sons?

Summary Answer: Maternal PCOS was associated with earlier adrenarche in daughters.

What Is Known Already: Female adolescents with PCOS often experience earlier adrenarche compared to adolescents without PCOS, due to hyperandrogenism. Likewise, they usually have hyperandrogenism during pregnancy, which might potentially affect the development of the foetus, including its future reproductive health.

Maternal Cigarette Smoking During Pregnancy and Genital Anomalies in Boys: A Register-Based Cohort and Sibling-Matched Design Study.

Purpose: Cryptorchidism and hypospadias share several prenatal risk factors. However, in published studies, boys exposed to cigarette smoking during pregnancy have a higher risk of cryptorchidism and a lower risk of hypospadias. Using Danish register-based data, we revisited these findings with a cohort and sibling-matched design to investigate the potential effect of shared time-stable factors.

Caesarean delivery and pubertal timing in boys and girls: A Danish population-based cohort study.

Background: There is considerable public and scientific interest in the declining age of pubertal timing. Prenatal and postnatal stress has been proposed to relate with earlier pubertal timing, but it remains unknown whether intrapartum stress may affect pubertal timing as well.

Objective: This study aims to examine the potential effect of caesarean delivery on pubertal timing in boys and girls.

The influence of parental age on timing of puberty: A study in the Danish National Birth Cohort.

Concerns have been raised about the potential negative biological effect of postponed parenthood upon the health of subsequent generations, including reproductive health. This study aimed to estimate if high parental age at birth was associated with accelerated pubertal timing in offspring. In this large-scale cohort study, 15,819 children born by mothers in the Danish National Birth Cohort from 2000 to 2003 participated in a nationwide puberty cohort (participation rate 71%).

Father Absence in Pregnancy or During Childhood and Pubertal Development in Girls and Boys: A Population-Based Cohort Study.

This cohort study, including 15,810 children born 2000-2003 in Denmark, aimed to investigate the association between father absence in pregnancy or during childhood and pubertal development in girls and boys. The children were followed from 11 years of age and throughout pubertal development. Mean age differences according to exposure groups were estimated for each pubertal marker separately and for a combined pubertal marker.

Hypertensive disorders in pregnancy and timing of pubertal development in daughters and sons.

Study Question: Do maternal hypertensive disorders affect pubertal development in daughters and sons?

Summary Answer: Pubertal development tended to occur earlier in daughters of mothers with 'preeclampsia, eclampsia or HELLP syndrome' (hemolysis, elevated liver enzymes and low blood platelets) or hypertension in pregnancy compared to daughters born of normotensive mothers.

What Is Known Already: The existing literature suggests some or no association between preeclampsia and pubertal development in daughters, but not in sons. None of the previous studies has investigated the possible association between other types of hypertensive disorders (hypertension, eclampsia or HELLP syndrome) and pubertal timing in children.

In Utero Exposure to Glucocorticoids and Pubertal Timing in Sons and Daughters.

Early pubertal timing has been associated with adult diseases, and identifying preventable causes is of importance. In utero exposure to exogenous glucocorticoids, has been associated with changes in the reproductive hormonal axes in the children, which may influence pubertal timing. Exogenous glucocorticoids can be indicated for diseases such as asthma, allergy, skin diseases, as well as muscle and joint diseases.